Heating element construction



Sept. 10, 1935. A. s. KNAPP ET AL 2,914,001

HEAT I NG ELEMENT CON STRUCTION Filed Aug, 17, 1955 vPatented Sept. 10,1935 UNITED STATES PATENT OFFICE Stevens, Chattanooga,

Tenn., assignors to Knapp-Monarch Company, Belleville, Ill., acorporation of Missouri Application August 17,

11 Claims.

An object of our present invention is to provide a. heating elementconstruction in which simple, durable and inexpensive means is providedfor supporting a resistance element relative to a plate or the like tobe heated thereby.

A further object is to provide a heating element construction comprisinga plate of sheet metal or the like having outwardly opening slots in theedge thereof and insulating elements received in the slots to projectoutwardly from the edge of the plate, the insulating elements havingnotches in their outer ends through which the resistance element extendsfor supporting it in relation tov the plate and insulating it therefrom.

A further object is to provide a heating element construction in whichinsulating elements can be associated with plates of various diametersfor making small or large diameter heating elements, the insulatingelements in each case being the same and the plate only being differentfor the different sizes of heating elements.

Another object is to provide a heating element consisting of a platehaving slots into which insulating elements may be inserted, theelements themselves being grooved so as to retain them against undesiredmovement in the slots and having notches of peculiar formation in theirouter ends whereby the resistance element may be inserted, but cannotreadily be disassociated from the notch after the entire heating elementis\ assembled.

A further object is to provide a method of manufacturing a heatingelement assembly comprising the steps of associating a plurality ofinsulating elements with a center plate so that they project outwardlybeyond the edge thereof and the mounting of a coiled resistance wire innotches formed in the outer ends of the insulating element.

A further object is to provide the insulating elements of greaterthickness than the diameter of the coiled resistance wire whereby whenthey are placed against a plate or the like to be heated by theresistance wire they hold the resistance wire spaced and insulated fromthe plate or the like.

With these and other objects in view our invention consists in theconstruction, arrangement and combination of the various parts of ourdevice, whereby the objects contemplated are attained, as hereinaftermore fully set forth, pointed out in our claims, and illustrated in theaccompanying drawing, in which:-

Figure 1 is a vertical sectional view through a wallie iron showing apair of my heating element constructions associated therewith.

1933, Serial No. 685,584

Figure 2 is a lay-out view of the heating elements only before they areconnected to the wallie grids of the Waffle iron.

Figure 3 is an outer end elevation of one of the insulating elementsused in our heating element construction showing the resistance elementbeing entered into the notch in the end thereof.

Figure 4 is a sectional view on the line 4-4 of Figure 3.

Figure 5 is a sectional view on the line 5-5 of Figure 2.

Figure 6 is a perspective view lating elements; and

Figure 7 is a diagrammatic view showing a greater number of insulatingelements being used on a larger supporting plate.

On the accompanying drawing, we have used the reference numerals I0 andI2 to indicate the lower and upper grids respectively of a waffle ironA. Suitable casings I4 and I6 are provided for heating elements B, whichembody our invention and which are secured to the grids.

Each heating element B comprises a plate I8, insulating elements 20 anda resistance element 22. The plate I 8 is provided with radially eX-tending, outwardly opening slots 24 circumferentially spaced around theperiphery there-of. The edges of the plate adjacent the sides of theslots are corrugated, as indicated at 26 (see Figures 2 and 5).

Each insulating element 20 is provided on opposite sides with a groove28.

The insulating elements are adapted to be inserted in the slots 24 ofthe plate I8 with the edges of the slots and the corrugations 26received in the grooves 28 which are Wide enough to accommodate both thethickness of the plate and the height of the corrugation. Thecorrugations serve to provide points of engagement rather' than surfacesof engagement, whereby a better frictional contact between theinsulating elements and the plate I8 is had.

The grooves 28 are closer to one edge of the insulating element 20 thanthe other so that when the plate I8 is assembled therewith, the platewill be quite close to the grid I0 or other surface to be heated by theheating element and can be secured thereto, as by a bolt 30 and a nut32. The insulating elements 20, it will be noted, are of greaterthickness than the diameter Of the resistance element 22 and accordinglywhen the edges of the insulating elements are placed in contact with thegrids IG and I2 or other surface to be heated, regardless of which edgeis so placed, they will be holding the resistance Wire of one of theinsugeneral directions. On larger spaced from the grid and thus preventelectrical contact between the wire and the grid. A depression 34 in theplate may be provided with contacts the grid to prevent undue strain onthe plate I8 when the nut 32 is tightened.

The resistance element 22 is strung through notches 36 which areprovided in the outer. ends of the insulating elements 20. Each notchhas an entry portion 36a at its outer end which is of slightly greaterWidth than the diameter of the resistance element, as shown in Figure 3,and the axis of which is at a slight angle relative to the axis of thebottom of the notch 36 Where the resistance element Iinally rests afterassembly.k

By this arrangement the resistance element dur ing assembly must beentered into the notch 36 while at an angle relative to the plane of theplate I 8 and when it assumes its finally assembled position, Which isparallel to the plane of the plate, it is retained in the notch by theentry portion 36a.

Three of the insulating elements, as indicated at 20a, may be providedwith rivets 38 for the ends of the resistance element wires 40. Anotherof the insulating elements, as indicated at 20h, may be provided with arivet 4| for one end of the resistance element and for one end of aterminal prong 42. Another insulating element, as indicated at 2Bc, maybe provided with a rivet 44 for a terminal prong 46 and one end of aleadwire 4U, all as shown in Figure 2.

InFigure 2, we have shown a plate provided with the insulating elementsprojecting radially in six plates, additional slots 24 can be providedand additional insulating elements used, such as shown in Figure 7, inwhich the insulating elements project in eight general directions.Smaller or larger plates with fewer or greater number of slots andinsulating elements, it will be obvious, can be thus used for assemblingdifferent sizes of heating elements, yet using the same insulatingelement regardless of size of the finished heating element.

The terminal prongs 42 and 46 are preferably extended through insulatingbushings 48 in the casing I4 which help to support the prongs andinsulate them from the Waile iron A. The corrugations 26 need notnecessarily be provided, although they are found desirable. Means otherthan the grooves 28 can be provided to prevent undesired movement of theinsulating elements relative to the slots 24 and other changes also maybe made without departing from the real spirit and purpose of ourinvention and it is our intention to cover by our claims, any modifiedforms of structure or use of mechanical equivalents, which may bereasonably included Within their scope;

We claim as our invention:

1. A heating element construction comprising a. circular supportingplate having outwardly opening slots in the periphery thereof,insulating elements received in said slots and having their outer endsspaced from said periphery and notched, a resistance element extendingthrough the notches of said outer ends and shoulders on said insulatingelements engaging a surface of said plate to prevent movement of saidinsulating ellertnent through said slot at right angles to said p a e.

2. A heating element construction comprising a supporting plate havingoutwardly opening slots in the edge thereof, insulating elementsreceived in said slots and having their outer ends spaced from the edgeof said plate, a resistance 22 and for lead element supported adjacentsaid outer ends, a terminal prong having one end supported by one oisaid insulating elements and a casing in enclosing and supportingrelation to said heating element construction and in supporting relation5 to said prong intermediate the ends thereof. Y

3. A heating element construction comprising a supporting plate havingperipheral notches, a. plurality of insulating elements each having opposite grooves associated with one oi said notches, 10 projectingoutwardly from said plate and having their outer ends spaced from saidedge and a resistance element encircling said insulating elements,supported thereby adjacent said outer ends and retaining said insulatingelements in position on said edge of said plate.

4. A heating element comprising a. supporting plate having spaced slotsin the edge thereof, a plurality of insulating elements received in saidslots and having grooves overlapping the edges of said slots, saidinsulating elements projecting from the edge of said plate and havingtheir outer ends spaced from said edge and a resistance elementsupported on said insulating elements adjacent their outer ends. 25

5. A heating element comprising a supporting plate having spaced slotsin the edge thereof, a plurality of insulating elements received in saidslots and having grooves overlapping the edges of said slots, saidinsulating elements projecting 30 from the edge oi said plate and havingtheir outer ends spaced from said edge and a resistance elementencircling said Vinsulating elements, supported thereby adjacent saidouter ends and retaining said insulating elements in position on saidplate.

6. A heating element construction comprising a circular supporting platehaving radially extending slots in the periphery thereof, a plurality ofinsulating elements received, one in each of 4,0 said slots, projectingfrom the edge of said plate, having shoulders engaging the surface ofsaid plate adjacent said slots and having their outer ends spaced fromsaid edge and a resistance element supported on said insulating elementsadjacent their outer ends.

7. A heating element comprising a supporting plate having slots in theedge thereof, insulating elements having grooves in the sides thereof,said insulating elements being received in said slots with the edges ofthe plate adjacent the slots therein received in said grooves and aresistance element supported on said insulating elements.

8. A heating element comprising a supporting plate having slots in theedge thereof, insulating elements having grooves in opposite sidesthereof, said insulating elements being received in said slots with theedges of the plate adjacent the slots therein received in said grooves,said insulating elements having notches in their outer ends and aresistance element extending through said notches.

9. A heating element comprising a supporting plate having slots in theedge thereof, insulating 05 elements having grooves in the sides thereofreceived in said slots with the edges of the plate adjacent y the slotstherein received in said grooves, lsaid plate having a plurality ofcorrugations in the edge thereof adjacent said slots, said grooves beingWide enough to embrace both the edges and the corrugations and aresistance element supported on said insulating elements.

l0. A heating element construction comprising a supporting plate havingoutwardly opening 7' slots in an edge thereof, insulating elementsreceived in said slots and having -their outer ends spaced from saidedge and notched, a resistance element extending through the notches ofsaidv outer ends and a pair of shoulders on at least one side of each ofsaid insulating elements engaging opposite surfaces of said plate toprevent movement of said insulating elements through said slots at rightangles to said plate.

11. A heating element comprising a supporting plate having a slot in theedge thereof, an .insulating element having a groove in at least oneside thereof, said insulating element being received in said slot withthe edge of said supporting plate adjacent the slot therein received insaid groove of said insulating element, and a resistance elementsupported on said insulating element.

FRANK J. STEVENS. ANDREW S. KNAPP.

